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A woman in her 60s presented with a 2-year history of an abnormal left second fingernail. A previous biopsy showed a pyogenic granuloma, and she had been treated with curettage and electrodessication. In the few months before presentation, she experienced partial nail loss and her nail had become painful with intermittent drainage. Her medical history was significant for streptococcal glomerulonephritis and 2 prior kidney transplants. Her medications included prednisone, tacrolimus, and mycophenolate mofetil. Physical examination of the left second fingernail showed a tender ulcerated nodule encompassing the nail bed with near-complete nail loss and purulent drainage (Figure 1, left). A nail biopsy was repeated by performing a 4-mm punch through the nail bed. The specimen was analyzed by histopathology with hematoxylin-eosin staining and once again showed a pyogenic granuloma–like response characterized by proliferating blood vessels in a background of fibrosis and reactive plasmacytic infiltration (Figure 1, right). Careful inspection of the pyogenic granulomatous process at higher power demonstrated atypical epithelioid and spindled cells adjacent to blood vessels.
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Subungual amelanotic melanoma
B. Perform immunohistochemical analysis on the biopsy specimen
The keys to the correct diagnosis are the history of progressive nail loss and pain, the physical examination findings of an ulcerated nodule with near-complete nail loss, and the biopsy results. Under low-power magnification, the biopsy specimen resembles a pyogenic granuloma, but clues to malignancy are the atypical epitheliotropic and dermal spindled and epithelioid cells. Immunohistochemistry with Melan-A highlights these cells, which are diagnostic of subungual acral lentiginous melanoma (Figure 2),1 at a Breslow depth of 1.18 mm. Cryotherapy (liquid nitrogen treatment) is a reasonable treatment for a pyogenic granuloma or a verruca (wart). Tissue culture is an appropriate technique when a diagnosis of bacterial, atypical bacterial, or deep fungal infection is considered. Reassurance is suitable for a patient evaluated for healing after a surgical procedure (electrodessication and curettage for pyogenic granuloma).
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Corresponding Author: Shari Lipner, MD, PhD, Department of Dermatology, Weill Cornell Medicine, 1305 York Ave, 9th Floor, New York, New York 10021 (SHL9032@med.cornell.edu).
Published Online: February 16, 2018. doi:10.1001/jama.2018.0179
Conflict of Interest Disclosures: The author has completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.
Meeting Presentation: This article was presented at the American Academy of Dermatology 2018 Annual Meeting; February 16, 2018; San Diego, California.
Additional Contributions: I thank Cynthia Magro, MD (Department of Pathology, Weill Cornell Medicine), for her help with the pathology and figure legends and thank the patient for providing permission to share her information. Dr Magro received no compensation for her contributions.
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